linux/drivers/i2c/busses/i2c-highlander.c
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   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * Renesas Solutions Highlander FPGA I2C/SMBus support.
   4 *
   5 * Supported devices: R0P7780LC0011RL, R0P7785LC0011RL
   6 *
   7 * Copyright (C) 2008  Paul Mundt
   8 * Copyright (C) 2008  Renesas Solutions Corp.
   9 * Copyright (C) 2008  Atom Create Engineering Co., Ltd.
  10 */
  11#include <linux/module.h>
  12#include <linux/interrupt.h>
  13#include <linux/i2c.h>
  14#include <linux/platform_device.h>
  15#include <linux/completion.h>
  16#include <linux/io.h>
  17#include <linux/delay.h>
  18#include <linux/slab.h>
  19
  20#define SMCR            0x00
  21#define SMCR_START      (1 << 0)
  22#define SMCR_IRIC       (1 << 1)
  23#define SMCR_BBSY       (1 << 2)
  24#define SMCR_ACKE       (1 << 3)
  25#define SMCR_RST        (1 << 4)
  26#define SMCR_IEIC       (1 << 6)
  27
  28#define SMSMADR         0x02
  29
  30#define SMMR            0x04
  31#define SMMR_MODE0      (1 << 0)
  32#define SMMR_MODE1      (1 << 1)
  33#define SMMR_CAP        (1 << 3)
  34#define SMMR_TMMD       (1 << 4)
  35#define SMMR_SP         (1 << 7)
  36
  37#define SMSADR          0x06
  38#define SMTRDR          0x46
  39
  40struct highlander_i2c_dev {
  41        struct device           *dev;
  42        void __iomem            *base;
  43        struct i2c_adapter      adapter;
  44        struct completion       cmd_complete;
  45        unsigned long           last_read_time;
  46        int                     irq;
  47        u8                      *buf;
  48        size_t                  buf_len;
  49};
  50
  51static bool iic_force_poll, iic_force_normal;
  52static int iic_timeout = 1000, iic_read_delay;
  53
  54static inline void highlander_i2c_irq_enable(struct highlander_i2c_dev *dev)
  55{
  56        iowrite16(ioread16(dev->base + SMCR) | SMCR_IEIC, dev->base + SMCR);
  57}
  58
  59static inline void highlander_i2c_irq_disable(struct highlander_i2c_dev *dev)
  60{
  61        iowrite16(ioread16(dev->base + SMCR) & ~SMCR_IEIC, dev->base + SMCR);
  62}
  63
  64static inline void highlander_i2c_start(struct highlander_i2c_dev *dev)
  65{
  66        iowrite16(ioread16(dev->base + SMCR) | SMCR_START, dev->base + SMCR);
  67}
  68
  69static inline void highlander_i2c_done(struct highlander_i2c_dev *dev)
  70{
  71        iowrite16(ioread16(dev->base + SMCR) | SMCR_IRIC, dev->base + SMCR);
  72}
  73
  74static void highlander_i2c_setup(struct highlander_i2c_dev *dev)
  75{
  76        u16 smmr;
  77
  78        smmr = ioread16(dev->base + SMMR);
  79        smmr |= SMMR_TMMD;
  80
  81        if (iic_force_normal)
  82                smmr &= ~SMMR_SP;
  83        else
  84                smmr |= SMMR_SP;
  85
  86        iowrite16(smmr, dev->base + SMMR);
  87}
  88
  89static void smbus_write_data(u8 *src, u16 *dst, int len)
  90{
  91        for (; len > 1; len -= 2) {
  92                *dst++ = be16_to_cpup((__be16 *)src);
  93                src += 2;
  94        }
  95
  96        if (len)
  97                *dst = *src << 8;
  98}
  99
 100static void smbus_read_data(u16 *src, u8 *dst, int len)
 101{
 102        for (; len > 1; len -= 2) {
 103                *(__be16 *)dst = cpu_to_be16p(src++);
 104                dst += 2;
 105        }
 106
 107        if (len)
 108                *dst = *src >> 8;
 109}
 110
 111static void highlander_i2c_command(struct highlander_i2c_dev *dev,
 112                                   u8 command, int len)
 113{
 114        unsigned int i;
 115        u16 cmd = (command << 8) | command;
 116
 117        for (i = 0; i < len; i += 2) {
 118                if (len - i == 1)
 119                        cmd = command << 8;
 120                iowrite16(cmd, dev->base + SMSADR + i);
 121                dev_dbg(dev->dev, "command data[%x] 0x%04x\n", i/2, cmd);
 122        }
 123}
 124
 125static int highlander_i2c_wait_for_bbsy(struct highlander_i2c_dev *dev)
 126{
 127        unsigned long timeout;
 128
 129        timeout = jiffies + msecs_to_jiffies(iic_timeout);
 130        while (ioread16(dev->base + SMCR) & SMCR_BBSY) {
 131                if (time_after(jiffies, timeout)) {
 132                        dev_warn(dev->dev, "timeout waiting for bus ready\n");
 133                        return -ETIMEDOUT;
 134                }
 135
 136                msleep(1);
 137        }
 138
 139        return 0;
 140}
 141
 142static int highlander_i2c_reset(struct highlander_i2c_dev *dev)
 143{
 144        iowrite16(ioread16(dev->base + SMCR) | SMCR_RST, dev->base + SMCR);
 145        return highlander_i2c_wait_for_bbsy(dev);
 146}
 147
 148static int highlander_i2c_wait_for_ack(struct highlander_i2c_dev *dev)
 149{
 150        u16 tmp = ioread16(dev->base + SMCR);
 151
 152        if ((tmp & (SMCR_IRIC | SMCR_ACKE)) == SMCR_ACKE) {
 153                dev_warn(dev->dev, "ack abnormality\n");
 154                return highlander_i2c_reset(dev);
 155        }
 156
 157        return 0;
 158}
 159
 160static irqreturn_t highlander_i2c_irq(int irq, void *dev_id)
 161{
 162        struct highlander_i2c_dev *dev = dev_id;
 163
 164        highlander_i2c_done(dev);
 165        complete(&dev->cmd_complete);
 166
 167        return IRQ_HANDLED;
 168}
 169
 170static void highlander_i2c_poll(struct highlander_i2c_dev *dev)
 171{
 172        unsigned long timeout;
 173        u16 smcr;
 174
 175        timeout = jiffies + msecs_to_jiffies(iic_timeout);
 176        for (;;) {
 177                smcr = ioread16(dev->base + SMCR);
 178
 179                /*
 180                 * Don't bother checking ACKE here, this and the reset
 181                 * are handled in highlander_i2c_wait_xfer_done() when
 182                 * waiting for the ACK.
 183                 */
 184
 185                if (smcr & SMCR_IRIC)
 186                        return;
 187                if (time_after(jiffies, timeout))
 188                        break;
 189
 190                cpu_relax();
 191                cond_resched();
 192        }
 193
 194        dev_err(dev->dev, "polling timed out\n");
 195}
 196
 197static inline int highlander_i2c_wait_xfer_done(struct highlander_i2c_dev *dev)
 198{
 199        if (dev->irq)
 200                wait_for_completion_timeout(&dev->cmd_complete,
 201                                          msecs_to_jiffies(iic_timeout));
 202        else
 203                /* busy looping, the IRQ of champions */
 204                highlander_i2c_poll(dev);
 205
 206        return highlander_i2c_wait_for_ack(dev);
 207}
 208
 209static int highlander_i2c_read(struct highlander_i2c_dev *dev)
 210{
 211        int i, cnt;
 212        u16 data[16];
 213
 214        if (highlander_i2c_wait_for_bbsy(dev))
 215                return -EAGAIN;
 216
 217        highlander_i2c_start(dev);
 218
 219        if (highlander_i2c_wait_xfer_done(dev)) {
 220                dev_err(dev->dev, "Arbitration loss\n");
 221                return -EAGAIN;
 222        }
 223
 224        /*
 225         * The R0P7780LC0011RL FPGA needs a significant delay between
 226         * data read cycles, otherwise the transceiver gets confused and
 227         * garbage is returned when the read is subsequently aborted.
 228         *
 229         * It is not sufficient to wait for BBSY.
 230         *
 231         * While this generally only applies to the older SH7780-based
 232         * Highlanders, the same issue can be observed on SH7785 ones,
 233         * albeit less frequently. SH7780-based Highlanders may need
 234         * this to be as high as 1000 ms.
 235         */
 236        if (iic_read_delay && time_before(jiffies, dev->last_read_time +
 237                                 msecs_to_jiffies(iic_read_delay)))
 238                msleep(jiffies_to_msecs((dev->last_read_time +
 239                                msecs_to_jiffies(iic_read_delay)) - jiffies));
 240
 241        cnt = (dev->buf_len + 1) >> 1;
 242        for (i = 0; i < cnt; i++) {
 243                data[i] = ioread16(dev->base + SMTRDR + (i * sizeof(u16)));
 244                dev_dbg(dev->dev, "read data[%x] 0x%04x\n", i, data[i]);
 245        }
 246
 247        smbus_read_data(data, dev->buf, dev->buf_len);
 248
 249        dev->last_read_time = jiffies;
 250
 251        return 0;
 252}
 253
 254static int highlander_i2c_write(struct highlander_i2c_dev *dev)
 255{
 256        int i, cnt;
 257        u16 data[16];
 258
 259        smbus_write_data(dev->buf, data, dev->buf_len);
 260
 261        cnt = (dev->buf_len + 1) >> 1;
 262        for (i = 0; i < cnt; i++) {
 263                iowrite16(data[i], dev->base + SMTRDR + (i * sizeof(u16)));
 264                dev_dbg(dev->dev, "write data[%x] 0x%04x\n", i, data[i]);
 265        }
 266
 267        if (highlander_i2c_wait_for_bbsy(dev))
 268                return -EAGAIN;
 269
 270        highlander_i2c_start(dev);
 271
 272        return highlander_i2c_wait_xfer_done(dev);
 273}
 274
 275static int highlander_i2c_smbus_xfer(struct i2c_adapter *adap, u16 addr,
 276                                  unsigned short flags, char read_write,
 277                                  u8 command, int size,
 278                                  union i2c_smbus_data *data)
 279{
 280        struct highlander_i2c_dev *dev = i2c_get_adapdata(adap);
 281        u16 tmp;
 282
 283        init_completion(&dev->cmd_complete);
 284
 285        dev_dbg(dev->dev, "addr %04x, command %02x, read_write %d, size %d\n",
 286                addr, command, read_write, size);
 287
 288        /*
 289         * Set up the buffer and transfer size
 290         */
 291        switch (size) {
 292        case I2C_SMBUS_BYTE_DATA:
 293                dev->buf = &data->byte;
 294                dev->buf_len = 1;
 295                break;
 296        case I2C_SMBUS_I2C_BLOCK_DATA:
 297                dev->buf = &data->block[1];
 298                dev->buf_len = data->block[0];
 299                break;
 300        default:
 301                dev_err(dev->dev, "unsupported command %d\n", size);
 302                return -EINVAL;
 303        }
 304
 305        /*
 306         * Encode the mode setting
 307         */
 308        tmp = ioread16(dev->base + SMMR);
 309        tmp &= ~(SMMR_MODE0 | SMMR_MODE1);
 310
 311        switch (dev->buf_len) {
 312        case 1:
 313                /* default */
 314                break;
 315        case 8:
 316                tmp |= SMMR_MODE0;
 317                break;
 318        case 16:
 319                tmp |= SMMR_MODE1;
 320                break;
 321        case 32:
 322                tmp |= (SMMR_MODE0 | SMMR_MODE1);
 323                break;
 324        default:
 325                dev_err(dev->dev, "unsupported xfer size %zu\n", dev->buf_len);
 326                return -EINVAL;
 327        }
 328
 329        iowrite16(tmp, dev->base + SMMR);
 330
 331        /* Ensure we're in a sane state */
 332        highlander_i2c_done(dev);
 333
 334        /* Set slave address */
 335        iowrite16((addr << 1) | read_write, dev->base + SMSMADR);
 336
 337        highlander_i2c_command(dev, command, dev->buf_len);
 338
 339        if (read_write == I2C_SMBUS_READ)
 340                return highlander_i2c_read(dev);
 341        else
 342                return highlander_i2c_write(dev);
 343}
 344
 345static u32 highlander_i2c_func(struct i2c_adapter *adapter)
 346{
 347        return I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_I2C_BLOCK;
 348}
 349
 350static const struct i2c_algorithm highlander_i2c_algo = {
 351        .smbus_xfer     = highlander_i2c_smbus_xfer,
 352        .functionality  = highlander_i2c_func,
 353};
 354
 355static int highlander_i2c_probe(struct platform_device *pdev)
 356{
 357        struct highlander_i2c_dev *dev;
 358        struct i2c_adapter *adap;
 359        struct resource *res;
 360        int ret;
 361
 362        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 363        if (unlikely(!res)) {
 364                dev_err(&pdev->dev, "no mem resource\n");
 365                return -ENODEV;
 366        }
 367
 368        dev = kzalloc(sizeof(struct highlander_i2c_dev), GFP_KERNEL);
 369        if (unlikely(!dev))
 370                return -ENOMEM;
 371
 372        dev->base = ioremap(res->start, resource_size(res));
 373        if (unlikely(!dev->base)) {
 374                ret = -ENXIO;
 375                goto err;
 376        }
 377
 378        dev->dev = &pdev->dev;
 379        platform_set_drvdata(pdev, dev);
 380
 381        dev->irq = platform_get_irq(pdev, 0);
 382        if (iic_force_poll)
 383                dev->irq = 0;
 384
 385        if (dev->irq) {
 386                ret = request_irq(dev->irq, highlander_i2c_irq, 0,
 387                                  pdev->name, dev);
 388                if (unlikely(ret))
 389                        goto err_unmap;
 390
 391                highlander_i2c_irq_enable(dev);
 392        } else {
 393                dev_notice(&pdev->dev, "no IRQ, using polling mode\n");
 394                highlander_i2c_irq_disable(dev);
 395        }
 396
 397        dev->last_read_time = jiffies;  /* initial read jiffies */
 398
 399        highlander_i2c_setup(dev);
 400
 401        adap = &dev->adapter;
 402        i2c_set_adapdata(adap, dev);
 403        adap->owner = THIS_MODULE;
 404        adap->class = I2C_CLASS_HWMON;
 405        strlcpy(adap->name, "HL FPGA I2C adapter", sizeof(adap->name));
 406        adap->algo = &highlander_i2c_algo;
 407        adap->dev.parent = &pdev->dev;
 408        adap->nr = pdev->id;
 409
 410        /*
 411         * Reset the adapter
 412         */
 413        ret = highlander_i2c_reset(dev);
 414        if (unlikely(ret)) {
 415                dev_err(&pdev->dev, "controller didn't come up\n");
 416                goto err_free_irq;
 417        }
 418
 419        ret = i2c_add_numbered_adapter(adap);
 420        if (unlikely(ret)) {
 421                dev_err(&pdev->dev, "failure adding adapter\n");
 422                goto err_free_irq;
 423        }
 424
 425        return 0;
 426
 427err_free_irq:
 428        if (dev->irq)
 429                free_irq(dev->irq, dev);
 430err_unmap:
 431        iounmap(dev->base);
 432err:
 433        kfree(dev);
 434
 435        return ret;
 436}
 437
 438static int highlander_i2c_remove(struct platform_device *pdev)
 439{
 440        struct highlander_i2c_dev *dev = platform_get_drvdata(pdev);
 441
 442        i2c_del_adapter(&dev->adapter);
 443
 444        if (dev->irq)
 445                free_irq(dev->irq, dev);
 446
 447        iounmap(dev->base);
 448        kfree(dev);
 449
 450        return 0;
 451}
 452
 453static struct platform_driver highlander_i2c_driver = {
 454        .driver         = {
 455                .name   = "i2c-highlander",
 456        },
 457
 458        .probe          = highlander_i2c_probe,
 459        .remove         = highlander_i2c_remove,
 460};
 461
 462module_platform_driver(highlander_i2c_driver);
 463
 464MODULE_AUTHOR("Paul Mundt");
 465MODULE_DESCRIPTION("Renesas Highlander FPGA I2C/SMBus adapter");
 466MODULE_LICENSE("GPL v2");
 467
 468module_param(iic_force_poll, bool, 0);
 469module_param(iic_force_normal, bool, 0);
 470module_param(iic_timeout, int, 0);
 471module_param(iic_read_delay, int, 0);
 472
 473MODULE_PARM_DESC(iic_force_poll, "Force polling mode");
 474MODULE_PARM_DESC(iic_force_normal,
 475                 "Force normal mode (100 kHz), default is fast mode (400 kHz)");
 476MODULE_PARM_DESC(iic_timeout, "Set timeout value in msecs (default 1000 ms)");
 477MODULE_PARM_DESC(iic_read_delay,
 478                 "Delay between data read cycles (default 0 ms)");
 479